Top-level talks between the German government, the U.S. and investors to save General Motors Corp.'s (GM) Adam Opel GmbH from insolvency will only take place if potential investors and GM agree on relevant points and if "substantial" plans, such as a letter of intent, are provided, the German government said Friday.

As a result, it's as yet unclear whether Friday's meeting between the government, the U.S. and investors to rescue Opel would take place, government spokesman Thomas Steg said told reporters.

State secretaries will assess the state of the negotiations at 1200 GMT and it will then be decided whether the top meeting with Chancellor Angela Merkel, government ministers, state governors, GM, representative for the U.S. Treasury and investors would talk place.

A meeting will only take place "if there's something to talk about" and "if the participants will present something substantial," Steg said.

At present, he expects the key meeting in the late afternoon to take place.

He said that it's unclear whether further talks might be needed but government officials would be available if meetings are necessary over the weekend.

Germany early Thursday delayed a decision on providing state-backed bridge financing to the Opel unit because GM on Wednesday submitted a surprise request for at least another EUR300 million in bridge financing from the German government, on top of the EUR1.5 billion already under discussion.

Steg said that the government would only back a bridge financing up to EUR1.5 billion but no more. He also said a rescue of Opel "won't take place at any cost."

Germany wants to safeguard jobs and production sites, but the impact on German taxpayers is also a key criteria.

Steg also said that it was no surprise that Fiat will not attend the meeting because Fiat isn't currently in talks with GM and the U.S. government while Magna still is.

But this doesn't mean that Fiat is no longer interested in bidding for Opel, Steg said.

By Andrea Thomas, Dow Jones Newswires; +49 (0)30-2888 410; andrea.thomas@dowjones.com